Geller



United States Patent COKING F BITUMINOUS SUBSTANCES Julius Geller, BadHomburg, Germany, assignor to Rutgerswerke-Aktiengesellschaft, Frankfurtam Main, Germany Application April 25, 1951, Serial No. 222,880

6 Claims. (Cl. 20217) Pitches fromcoal or lignite tar, high boilingmineral oil residues or the like are coked in furnaces of relativelygreat capacity at temperatures of about 1000". This entails extremelylong refining times, as the fairly wide furnace chambers make arelatively low coking speed possible. Moreover the pitches contain, whenbeing charged, over 40 volatile constituents, so that up to the start ofthe formation of coke great quantities of liquid have to be evaported.The charging of large quantities of. pitch or residues into the chambersentails the further disadvantage that the liquid material undertreatment has a very detrimental effect on the refractory masonry of thechambers. In addition, owing to the considerable variations intemperature of the large quantities of pitch charged into the chambersthe furnace masonry is subjected to considerable temperature variationswhich, after the furnace has been in operation for a relatively shortperiod, cause leakages and damage to the masonry.

In order to avoid these disadvantages of the known intermittent cokingprocess it has already been proposed toinject pitches or oils in afinely divided state into a larger coking chamber. With this method,however, the relatively limited dropping distance is insufficient forconverting the pitch or oil drops into the solid state before theystrike the chamber wall. Consequently, even after a relatively shortoperational period, caked-together pieces of coke are formed, whichbecomeunevenly baked and in addition can only be removed from thechamber with difiiculty.

' Now it has been found that a uniform and rapid formation of coke canbe obtained if the material under treatment, which may. be preheated, isfreed above its melting temperature through distillation, oxidation orpolymerisation or the like from its volatile constituents until itreaches the viscous state and is then converted through the action ofhigh temperature into the solid state. The proposed preliminary refiningcan be carried out in relatively simple arrangements, for instance incolumns with filling material or bell-bottom columns. The residualvolatile constituents still contained in the material can be driven outvery rapidly, so that the material is converted in a relatively shorttime from the liquid to the solid state.

, The new process can, be carried out withspecial advantage, if thepreliminarily refined and viscous mate- 'rial in a finely and as far aspossible evenly divided state, forinstance inthe form of drops, jets orhands, be'converted into thesolid state. Through the uniform shape givento'the material a uniform heating and consequently a uniform cokeformation will also be assured, so that 'with the novel mode ofoperation adaptation to a great variety of conditions as-regards qualitybecomes possible. In order that the transmission of heat to the materialshall'not be'detrimentally affected, when the coking chamber is heatedindirectly, according to the invention the material is conveyed in afree downward or upward posits on the walls, which would reduce thetransmission of heat, are avoided. At the same time the refractorylining of the coking chamber is as far as possible preserved frominjuries.

For many purposes of use the coke made from mineral oil residues orpitches should contain as few volatile constituents as possible or evenpractically none. According to the present invention, therefore, theresidual volatile constituents of the coke are driven out by calcinationwith direct or indirect heating. Particularly simple conditions areobtained, when the heat required for calcining is made available by thecombustion of a corresponding part of the coke. The partial combustionmust, however, lead to as uniform as possible a calcining of the entirecharge. Provision is therefore made in the partial combustion of thecoke to cause the combustion air and the combustion products to flow ina uniformly distributed state either from the centre of the calciningchamber radially outwards or from the periphery of this chamber radiallyinwards, the fuel bed being, if required, kept in heaving motion.

Through the coke bed being uniformly supplied with the combustion airand the furnace gases as they form a correspondingly uniform temperaturedistribution within the calcining chamber will result and also acorrespondingly uniform expulsion of the residual volatileconstitutents.

In the partial combustion of the coke not only furnace gases, but alsostill combustible gases are formed. It is therefore proposed accordingto the invention to burn the gases drawn by suction from the calciningchamber, under certain circumstances together with other fluid orgaseous fuels and to use the hot furnace gases for the direct orindirect heating of the coking chamber and in certain circumstances ofthe distilling column or refiner for the bituminous substance as well.In this way the heat consumption of the whole process is reduced to aminimum. 7

Since in the case of indirect heating of coking chamber the escape ofthe products of combustion and generator gases out of the calciningchamber directly into the coking chamber is undesirable, according tothe invention the coke is piled up in the calcining chamber so as toreach above the gas outlet at the outer periphery of this zone.

As the calcining of the coke takes place at temperatures above 1000",the calcined coke must be directly or indirectly cooled before leavingthe apparatus. Direct cooling can be effected with water vapour, so thatwater gas is still formed at the lower end of the calcining zone. Thewater gas can then be made use of for heating the coking chamber.

Thenew process can be carried out in a particularly simple manner, ifthe bituminous material be freed in a distilling column, a refiner orthe like from a substantial part of its volatile constituents andthereupon be conveyed into an upright, preferably cylindrical shaft, inwhich the coking, calcining and cooling chambers are arranged dire ctly.one under the other.

According to the invention the distilling column may be arranged abovethe coking chamber, so that the pitch which is driven off will pass outof the column directly into the coking chamber. The bottom wall of thecolumn is so constructed that the pitch enters the coking chamber in adefinite form as drops, a band or a jet of definite dimensions.

If the apparatus for the preliminary driving off of the bituminoussubstance andvthe coking chamber be heated indirectly, according to theinventionthe two will be provided each with a jacket for conveying theheating gases, the space between the inner and outer jacket beingbounded at the top and bottom in each case by a collecting channel.These collecting channels serve the purpose of supplying and conveyingaway the heating gases. In order, however, to ensure a uniform flow ofgas within the heating space and to equalise the one-sided motion of theinflow and outflow ducts, according to the invention the freecross-section area between the heating gas space and the collectingchannel becomes smaller and smaller as the distance from the connectingpipe diminishes. Through suitably dimensioning the free cross-section itbecomes possible to obtain a very uniform supply of heating gases to thechamber walls.

For conveying away the furnace gases and the like from the calciningchamber the lower collecting channel of the coking chamber is connectedby a narrow opening with the upper end of the calcining chamber. In thisway the gaseous products of the calcining chamber can be made availablefor the indirect heating of the coking chamber in a very simple manner.

According to the invention the supply of the combustion air to thecalcining chamber takes place through one or more pipes extending toabout the middle of this chamber and provided in certain circumstanceswith water cooling means. It is of course also possible to convey thecombustion air, the produced furnace gases and so forth inside thecalcining chamber radially from the outside to the inside. In this casean annular gap for the inlet of the combustion air must be provided atthe outer periphery of the calcining chamber, whilst the furnace gasesand so forth are conveyed away from the middle of the calcining chamberand conveyed to the heating jacket of the coking chamber.

In the accompanying drawing a constructional example of an apparatusaccording to the invention is illustrated diagrammatically. Figure 1illustrates the apparatus in vertical sectional view, while Figure 2 isa fragmentary vertical section through a modification of a part of theheating jacket. The apparatus consists substantially of the refiner 1and the shaft furnace 2. The coal tar pitch to be coked passes throughthe connection 3 into the refiner 1 and flows there on sheet metaldeflectors 4 downwards in a relatively thin film.

The refiner is provided with a heating jacket 5 for conveying theheating gases. These gases enter through the opening 6 into the channel7 and flow through the narrow space 8 upwards in a uniformly distributedstate. At the upper end of the heating jacket 5 is the annular channel9, out of which the heating gases are drawn by suction through theopening 10. According to the properties and the composition of the pitchand the pressure prevailing in the refiner, the latter is heated up to atemperature of from 300 to 500. The vapours liberated from the pitch areconveyed away through the opening 11.

In order to reduce the evaporation temperature of the pitch, superheatedwater vapour or any other carrier gas can be conveyed to the refinerthrough the opening 12.

The evaporation of the more readily boiling pitch constituents is socontrolled that the pitch will at the particular working temperaturepass into the distributer 13 in the viscous state. In general coal tarpitch will then still contain only about 20% volatile constituents. Thedistributer 13 is provided with numerous bottom openings, so that thepitch will pass into the coking chamber 14 in a corresponding number ofthin jets. Forming a downward continuation of this coking chamber arethe calcining chamber 15 and the cooling chamber 16. The calcined andcooled pitch coke is discharged in such a manner by the worm 17 that thecoke within the shaft furnace will remain piled up to the upper end ofthe calcining chamber 15. On the other hand, the coking chamber 14 isfilled only by gases and vapours and freely falling jets of pitch.

The coking chamber 14 is surrounded by a heating jacket 18 for conveyingthe heating gases. These gases enter through theopening 19 into theannular channel 20 and then flow in a uniformly distributed statethrough the narrow space 21 upwards. At the upper end of the col:-

ing chamber 14 the heating gases collect in the annular channel 22 andare drawn ofi by suction through the opening 23. A portion of theheating gases can be conveyed into the annular channel 7 for heating therefiner 1. The other portion of the waste gases can be used forpreheating the combustion air or the pitch.

During the free fall of the relatively thin jets of pitch through thecoking chamber 14 the residual volatile constituents are evaporated sorapidly and to such an extent under the reaction of the chamber wallswhich are heated to over 1000 that the pitch is converted into the solidstate. The calcining chamber 15 is therefor filled with a relativelyfine grain pitch granulate which still contains a few volatileconstituents. As, however, the pitch coke is in general to be as free aspossible from volatile constituents for the subsequent purposes of use,a suitable calcining takes place in the chamber 15.

In the present constructional example the heat required for this purposeis produced by the combustion of a portion of the coke. For this purposeair is introduced through one, two or more horizontally arranged pipes24 into the middle of the calcining chamber. In view of the hightemperature the pipes are either made of highly fireresistant materialor are cooled with a suitable cooling medium, for instance water. It isalso of advantage, when the air is supplied through a plurality ofpipes, to arrange the latter symmetrically, in order to bring about auniform fiow of gas within the shaft. The quantity of air conveyed inthrough each pipe may be regulated independently in any suitable manner.

The gaseous combustion products formed and the volatile constituentsdriven out of the coke fiow within the shaft from the middle upwards andto the side and pass through the slits 25 into the annular channel 20.Through the symmetrical supply of the combustion air and through itbeing conveyed away symmetrically a symmetrical rotary fiow of gas isformed within the shaft, so that the pitch coke is calcined uniformly.

The volatile constituents which are driven off in the calcining zoneserves the purpose of heating the coking chamber 14. For this purposethe annular channel 20 is supplied through the opening 19 with acorresponding amount of combustion air. Should the volatileconstituents, however, be insufficient for heating the coking chamber 14and the refiner 1, the annular channel 20 can be supplied withadditional liquid or gaseous fuel and a corresponding amount ofcombustion air. The com bustion air will with advantage be considerablyreheated in an air preheater.

From the calcining chamber 15 the pitch coke passes into the coolingchamber 16 which is surrounded by a cooling jacket 26. Here a suitablecooling medium, for instance water, enters through the opening 27 andleaves the cooling jacket through the opening 28.

The worm 17 conveys the pitch coke continuously out of the shaftfurnace. Through a suitable construction the worm can to a considerableextent seal the shaft furnace with respect to the atmosphere.

In order to heat the walls of the shaft furnace and of the refineruniformly, provision must be made for a correspondingly uniformdistribution of the heating gases. For this purpose the annular channel22 is provided, as will be seen from Figure 2, with a throttling strip,the height of which decreases as the distance increases. For showingthis more clearly, the annular channel 22 is shown in Figure 2 to alarger scale. As will be seen, the throttling strip 29 decreases itsheight as its distance from the connecting opening 23 increases, thisbeing indicated by a dotted line. To a corresponding extent the freecross-section of the gap 30 for the gases increases as the distance fromthe opening 23 increases. In this way the shaft furnace is fed uniformlywith the heating gases along its entire periphery.

According to the material to be coked the temperatures of the chambers14 and 15 range from 900 to 1400 preferably. The walls, moreparticularly at the higher temperatures, will be made of a refractorymaterial. The wall of the cooling chamber 16, however, will preferablybe made of sheet iron.

I claim:

1. A process for coking pitch from coal tar, lignite tar, and highboiling mineral oil residue, as well as similar meltable bituminousstarting materials containing over 40% high boiling volatile ingredientscomprising passing the starting material downwardly through a distillingzone, subjecting the material while passing through said zone todistillation eifected by heat applied extraneously to the wall of thezone to convert the material into a viscous mass containing only about20% of volatile constituents, discharging vapors from the distillationof the starting material from the upper portion of said distilling zone,dividing the viscous mass of material as it emerges from the lowerportion of the distilling zone into streams, dropping them downwardly asfree falling particles through a coking zone positioned directly beneaththe distilling zone, heating the particles of viscous material as theyfall through the coking zone by radiant heat applied extraneously to thewalls of the coking zone the path of fall being suificient to convertthe viscous particles into coke particles, collecting the coke particlesin a calcining zone beneath the coking zone, and heating the cokeparticles to a temperature of over l000 to remove remaining volatileconstituents.

2. A process according to claim 1 in which the solid particles areheated by burning a portion of the coke in the lower portion of thecalcining zone and passing the products of combustion upwardly throughthe calcining zone, removing the products of combustion and entrainedvolatile material from the upper portion of the calcining zone, anddischarging coke from the lower portion of the calcining zone at a ratecorrelated with the feed of starting material, to maintain the level ofsolid particles extending up into the lower portion of the coking zoneto reduce the tendency of the products of combustion and entrainedvolatile material to enter the coking zone.

3. A process according to claim 2 in which the products of combustiondischarged from the upper portion of the calcining zone are passed inheat exchange relation with the exterior of the walls of the coking zoneto extraneously heat said walls.

4. Apparatus for coking pitch from coal tar, lignite tar, and highboiling mineral oil residue, as well as similar meltable bituminousstarting materials containing highboiling volatile ingredientscomprising an elongated vertically extending coking chamber, a heatingjacket surrounding the coking chamber, a distilling column positioned onthe upper portion of the coking chamber in vertical alignment and indirect communication therewith, a heating jacket surrounding thedistilling column, means for introducing starting material into theupper portion of the distilling column, said column having an outlet inits upper portion for discharge of volatile material, means at the lowerportion of the distilling column for dividing viscous material resultingfrom distillation of the starting material and dropping it into theupper portion of the coking chamber for free falling downwardly throughthe coking chamber, a calcining chamber positioned beneath the cokingchamber in vertical alignment and in direct communication therewith forreceiving coked particles from the coking chamber, means for feedingcombustion supporting air into the lower portion of the calciningchamber, the upper portion of the calcining chamber being of larger areathan the lower portion of the coking chamber to provide a discharge atthe upper peripheral portion of the calcining chamber for products ofcombustion.

5. Apparatus according to claim 4 further comprising means forcontrolling the discharge of coked particles from the lower portion ofthe calcining chamber to maintain a body of particles in the calciningchamber extending up into the lower portion of the coking chamber toclose the lower portion of the coking chamber whereby gases from thecalcining chamber are introduced into the jacket surrounding the cokingchamber.

6. Apparatus according to claim 4 in which each heating jacket isbounded at the top and bottom by a collecting channel, the bottomcollecting channels having an opening for the introduction of a heatinggas and the collecting channels at the top each having an opening forthe discharge of heating gas and provided with a throttling strip, theheight of which decreases with the distance of the strip from theopening.

References Cited in the file of this patent UNITED STATES PATENTS830,248 Von Orth Sept. 4, 1906 842,170 Bryant et al J an. 29, 19071,358,663 Wallace Nov. 9, 1920 1,490,354 Wallace et al Apr. 15, 19241,637,683 Clarkson Aug. 2, 1927 1,805,711 Andrews et a1 May 19, 19312,131,702 Berry Sept. 27, 1938 2,179,080 Alther Nov. 7, 1939 2,237,414Day Apr. 8, 1941 2,366,057 Russell Dec. 26, 1944 2,448,223 Lantz Aug.31, 1948

4. APPARATUS FOR COKING PITCH FROM COAL TAR, LIGNITE TAR, AND HIGHBOILING MINERAL OIL RESIDUE, AS WELL AS SIMILAR MELTABLE BITUMINOUSSTARTING MATERIALS CONTAINING HIGHBOILING VOLATILE INGREDIENTSCOMPRISING AN ELONGATED VERTICALLY EXTENDING COKING CHAMBER, A HEATINGJACKET SURROUNDING THE COKING CHAMBER, A DISTILLING COLUMN IN TIONED ONTHE UPPER PORTION OF THE COKING CHAMBER IN VERTICAL ALIGNMENT AND INDIRECT COMMUNICATION THEREWITH, A HEATING JACKET SURROUNDING THEDISTILLING COLUMN, MEANS FOR INTRODUCING STARTING MATERIAL INTO THEUPPER PORTION OF THE DISTILLING COLUMN, SAID COLUMN HAVING AN OUTLET INITS UPPER PORTION FOR DISCHARGE OF VOLATILE MATERIAL, MEANS AT THE LOWERPORTION OF THE DISTILLING COLUMN FOR DIVIDING VISCOUS MATERIAL RESULTINGFROM DISTILLATION OF THE STARTING MATERIAL AND DROPPING IT INTO THEUPPER PORTION OF THE COKING CHAMBER FOR FREE FALLING DOWNWARDLY THROUGHTHE COKING CHAMBER, A CALCINING CHAMBER POSITIONED BENEATH THE COKINGCHAMBER IN VERTICAL ALIGNMENT AND IN DIRECT COMMUNICATION THEREWITH FORRECEIVING COKED PARTICLES FROM THE COKING CHAMBER, MEANS FOR FEEDINGCOMBUSTION SUPPORTING AIR INTO THE LOWER PORTION OF THE CALCININGCHAMBER, THE UPPER PORTION OF THE CALCINING CHAMBER BEING OF LARGER AREATHAN THE LOWER PORTION OF THE COKING CHAMBER TO PROVIDE A DISCHARGE ATTHE UPPER PERIPHERAL PORTION OF THE CALCINING CHAMBER FOR PRODUCTS OFCOMBUSTION.